Lifting fork with gripping means



Nm 2l, 1950 v. H. cAR'rwRxGHT 2,530,375

v LIFTNG FORK WITH GRIPPING MEANS Filed June 11, 194e 7 sheets-sheet 1 SIMS!) 55 aww/Hiob WCTOR H. CARTWWGHT,

A1 TORNEYJ'.

Nav. 2l, w50

v. H. cARTwRlGHT LIFTING FOK WITH GRIPPING MEANS 7 Sheets-Sheet 2 Filed June ll, 1948 T.. 1 l. 2. mm vn@ www ww La@ Tm w m6 vn i.. 1 l VEL- l?. /mm\\ww @www A lomm imm mi w q T. ,-wH--:%m nu Nm Lm mm I I i l I l I I i l l f {@Wlll Illilwl. www f3 mm Nov.. 21, 1950 v. H. CARTWRKGHT LIFTING Foxx wrm GRIPPING MEANS '7 Sheets-Sheet7 Filed June l1, 1948 v|cToR H.- cARTwRiGHr orneys Num 2E, 195@ v. H, CARTWRlGH-r 2,530,3?5

LIFTING FORK WITH GRIPPING MEANS Filed June 1l, 1948 7 Sheets-Shea?. 4

38a 52o @a VICTOR H. CAR'TWRIGHT,

Aitomeys.

Nov. 21, 1950 v. H. cARTwRlGl-rr LIFTING'FoRx wrm GRI'PPING mms 'r sheets-smet 5 Filed June l1, 1948 In In VIC TOR H. CARTWMGHT umm Nov. 21, 195o {,1 H, CARTWHGHT 2,530,375

LIFTING FORK WITH GRIPPING MEANS Filed June 11, i548 7 snets-sneei 'e FIG. I3 FIG. I4 7' 4 69 7,0 71| 59 l5- 54 At orneys,

NOV- 21, 1950 v. H. cARTwRlGl-IT 2,530,375

LIFTING FORK WITH GRIPPING MEANS Filed June 11. 1948 7 Sheets-Sheet 7 FIG.. I7

VlGTOR H. CARTWRIGHT,

Patented Nov. 21, 1950 UNITED STATES PATENT OFFICEl Llr'rmG Fonx WITH GRIPPING MEANS Victor H. Cartwright, Dunlap, Ill. Application June 11, 194s, serial No. 32,550

7 Claims. 1

This invention relates to a device for handling and transporting materials, and more particularly to a device for the lifting and transporting en masse of bricks, or similar materials.

In the handling of large numbers of small units of identical material, such as bricks it is uneconomic to handle each unit separately in the various stages of manufacture, sale, and use in addition to incidental movements to and from storage. It is desirable to stack such units in piles of more or less uniform size, each of which piles may easily be handled by small mobile fork trucks. The usual type of fork truck consists primarily of a series of horizontal arms mounted on a self-powered wheeled chassis in such a way that the arms may be lowered close to the ground, and slid beneath a stack of objects, after which the objects may be raised and carried tothe desired location, and put back upon the ground. However, the objects must be iirst placed upon a raised platform, or pallet,under which the arms of the fork truck may be slid. -A large number of objects may be thus placed upon a pallet and handled together as a unit, the principal disadvantage being that the pallets themselves do not form a part of the useful load, and if there is a steady movement of -materials from one point to another in only one direction, there must be a continual replacement of the pallets, or provision must be made for their return tothe point of origin.

It is therefore an object of this invention to l provide a device which may be used with the conventional fork truck to transport as unitary loads, materials which may be compactly stacked in piles containing large numbers of units. Such materials are usually arranged so that the bottom row is not a solid mass but consists of a selves. It will be observed that the effect of this apparatus is to eliminate the necessity for a pallet, inasmuch as a sort of pallet is formed by vthe nger courses.

Another object of the device is to provide a materials handling means of the type described in which the clamping means are resiliently mounted. Y

`A further object of the device is to provide a lifting fork in which the clamping means are.ad justable,vand so arranged that regardless of the total weight of the load to be carried, the clamping means will not exert more than a predetermined amount of pressure upon the materials handled, resulting in less damage to the materials.

Other objects of the device will be apparent as the description of the invention progresses.

In the drawings accompanying this specication:

Figure 1 is a view in elevation, of the device mounted for use on a conventional fork truck;

Figure 2 is a view in elevation, of the device removed from the truck;

Figure 3 is a front view of the supporting frame;

Figure 4 is a side elevation of the supporting frame; Figure 5 is a top view of the supporting frame which is attached to a conventional fork truck;

Figure 6 is a front view of the vertical portion of the movable frame;

Figure 7 is a side view of the vertical portion of the movable frame;

Figure 8 is a top view of thevertical portion of the movable frame;

Figure 9 is a section taken on the line 9 9 of Figure 6;

Figure 10 is a top view of the horizontal portion of the movable frame;

Figure 11 is a top view of one of the horizontal arms; Figure 12 is a view in elevation of one of the horizontal arms;

Figure 13 is a view in elevation showing a detail of the clamping means;

Figure 14 is a section taken on the line II-H of Figure 13;

Figure 15 is a section taken on the line l5-I5 of Figure 14;

Figure 16 is a section taken on the line IE-IG of Figure 13;

Figure 1'? is a section taken on the line I'I--II of Figure l1; and

Figure 18 is a section taken on the line l8-l8 of Figure 11.

Referring now to the drawings in detail, the device is shown in Figure 1 mounted upon a conventional fork truck represented generally by the reference numeral 26. At the front of the truck there is usually provided a. carrier framework 2i mounted upon the chassis of the truck for vertical movement, which is actuated by the power plant of the truck, under control of the operator. To the carrier framework of the truck there is attached the supporting frame 22. which in turn carries the movable framework 23 in a manner to be described.

The supporting frame is Shown in detail in Figures 3, 4 and 5. This frame comprises a pair of vertical members 25, provided with horizontal members 26 and 21. Compensating springs 30 are attached at their upper ends to eye-bolts 3|, the threaded ends of which extend through openings provided in member 26, and are adjustably held in place by nuts 32. Vertical rods 28 are threaded at their upper ends, which pass loosely through suitable holes in support 21, and nuts 29 and 29a permit the rods to be individually adjusted in a vertical direction with respect to support 21. Brackets 34, attached to the upper ends kof the supports are provided with holes 35, and lugs 33, attached at the lower ends of the supports enable the supporting frame'22 to be removably attached to the carrier framework 2|, as shown in Figure 1.

The front and back surfaces 25a and 25h respectively, of the vertical supports are preferably flat in order to provide bearing surfaces for the movable framework.

The movable framework is shown in detail in Figures 6, 7, 8 and 9, and comprises a. pair of vertical members 36, joined together near their upper extremities by the member 31, and at the bottom by the relatively heavy member 38. To provide greater strength, the corner pieces 39 may be provided where members 36 are joined to member 38. Suitable means to attach the lower ends of the compensating springs 30 (see Figure 3) to the movable frame are provided by holes 39a drilled in plates 39.

The movable frame is supported for relative vertical movement with respect to the supporting framework by pairs of rollers, one pair of which 45 bears against the surfaces 25a, the other pair of which 42 bears against the surfaces 25b, respectively, of members 25. The rollers 45 are attached to members 36 by means of axles 44 supported by lugs 43, While lugs 46 provide support for the axles 4| on which rollers 42 revolve. of the movable framework is controlled by adjustable stops 41 threaded in the horizontal member 31 and provided with locking nuts 48. Guides 46, which project backwardly from the outer edges of members 36, partially surround Athe vertical members 25 of the supporting framework, and assist in maintaining the movable framework in alignment.

The heavy horizontal member 38 serves as the support for the forwardly extending arms The downward limit of movement 5| and 5|a. Projecting rearwardly from the member 38, behind each of the arms 5| and Sla, are bosses 49. Triangularly shaped Plates are pivotally mounted on bosses 49 for rotation about a horizontal axis at point 59a. Openings are provided in the plates at 50h, to permit pivotal connection with the lower ends of rods 28 (see Figure 3), and at 56e to permit pivotal connection with operating rods to be later described. Openings 38a are provided in the member 38 to accommodate these operating rods. (See Figure 10.) In Figure 10, there is shown a plan view of the preferred form of the arrangement of the horizontally spaced arms 5| and Sla. The arms are provided with movable clamping means 66, and it will be noted that arms 5| are provided with clamping means on both sides, while arms 5|a are provided with clamping means 60 on the inner side only. Clamping means on adjacent arms are preferably vdisposed in a cooperative relationship so as to grip articles, or material, between the arms when the clamping means are moved outwardly. It will be realized, however, that it is not necessary for successful operation of the device that movable clamping means be provided to grip both sides of the articles or material to be handled between the spaced arms. It will be obvious that so long as there is a movable clamping means provided on one side of the article to be handled the adjacent arm will cooperate with the movable means to gripthat article.

Arms 5| and 5|a comprise a pair of substantially U-shaped members 53a and 53h, supported on base plates 52 in spaced relationship with the legs of the U extending outwardly as shown in Figure 14. The cover plate 54 is attached to members 53a and 53h by means of bolts 58 which extend through countersunk slots 54h provided in the cover plate. The rear portion 54a of slots 54h is enlarged to allow quick removal of the cover plate. Base plates 52 may be welded, or bolted, to the horizontal member 38. Operating rods 55, which extend through openings 38a and 52a, provided in members 38 and plates 52, are supported in the spaces between members 53a and 53h on pins 56 so as to be capable of lateral movement with respect to the arms 5| and 5|a in response to vertical movement of rods 26, connected to the pivoted plates 50 (see Figure '1).

vertically disposed pivot pins 59 are placed on both sides of the inner arms 5|, while on arms 5|a they are provided on the inner side only. The clamping means 60 are supported for horizontal movement on these pivot pins. Each of the clamping means may comprise a rod, or heavy wire 6|, of resilient material such as spring steel which is formed at 6 la so as to loosely encircle the pivot pin 59 with its ends extending outwardly to provide leverage for operation of the clamping means. One end 6|c of the resilient rod may be bent in the shape of an eye. A pair of clamping plates 10 maybe provided with openings at 10a through which passes pivot pin 69, which also passes through the eye 6|c, the eye being placed between the clamping plates. It is to be understood that the clamping plates 18 are capable of rotation about a vertical axis with respect to the resilient rod 6|, but that it is immaterial whether the pivot pin is fixed to the rod and rotatably attached to the clamping plates, or vice versa. It will also be understood that the portion 6|c need not be turned in the manner shown. If desired the pivot pin 69 may be fixed to the rod 6| as by spot-welding, or other means. In order to increase the gripping action of the clamping plates 10, they may be covered at their extremities by rubber sleeves 1|.

Operating rods 55 are .provided with bosses 62 disposed at points adjacent the clamping means 60. Drilled lengthwise are holes 62a, through which extend the bolts 64. Threaded on the end of these bolts are blocks 63 which-are provided with tapered slots 63a. The outwardly extending ends 6|b, of the resilient rods 6|,` pass through slots 68 provided in the arms 53a a'nd 53h, and are operatively engaged by the tapered slots 63a so that lateral movement of 'operating rods 55 in one direction will cause the clamping means 80 to swing out horizontally away from the arms 5| and Sla, and movement of operating rods 55 in the other direction will cause the clamping means 60 .to be withdrawn inwardly. The extent of outward movement of clamping means 60 may be individually adjusted by turning the bolts 64 to increase, or decrease the distance between the blocks B3 and bosses 62. The adjustment may be maintained by means o f set screws 65a. Nuts 65h .and 65e, when drawn up against each other allow bolts 64 to turn freely in bosses 62, while limiting .axial movement.

The operation of the device may best be understood by referring to Figure 2, in which the lifting fork is shown in its lowered position in solid lines, ready to be moved into position between the finger courses of a stack of bricks (for example). When the'lifting fork has been placed in position by the` operator of the truck, the carrier frame 2| is raised, causing the supporting framework 22 to rise vertically also. While this occurs, the movable frame 23 would remain in place were it not for the fact that the compensating springs 30 exert lifting force on it as soon as the supporting frame begins to lift. However, as soon as the horizontal arms 5l and Sla are brought up against the under side of the bottom row of bricks supported by the finger courses, the Weight of the bricks above the arms will resist further upward movement of the movable framework 23 although movement of the supporting frame continues until the stops 41 abut against the horizontal member 21 of the supporting framework 22, at which point relative movement of the supporting frame with respect to the movable frame will cease, and further elevation of the carrier frame 2i will cause the entire stack of bricks/ (above the nger courses) to be raised by the horizontal arms 5I and Sla. During the period of relative movement between the supporting frame and the movable frame there will also be an upward movement of the rods 28 with respect to the movable framework 23 which will cause plates 50 to rotate about their axes 50a upwardly, thus drawing back the operating rods 55. This movement of the operating rods causes the various clamping means 60 to swing outwardly and resiliently grasp the bricks comprising the finger courses, which will also be lifted from the ground with the rest of the stack, supported on top of the horizontal arms 5i and Sla. The broken lines in Figure 2 represent the position of the various elements when the carrier of the fork truck Vis in its raised position. It should be noted that, because stops 41 limit the amount of relative movement between the supporting frame and the movable frame, the lifting forces are not transmitted through clamping means 60 to the bricks comprising the finger courses. The pressure exerted by the clamping means may be adjusted by means of bolts 64 (see Figures 15 and 16) When the bricks have been carried to the desired location, the operator of the fork truck lowers the carrier frame 2|, and as soon as there is relative movement between the supporting frame 22 and movable frame 23 the operating rods will move forwardly to positively retract theY clamping means` 60. At the lowermost position of the carrier frame the horizontal arms 5l and Ela will have dropped below the row of bricks supported on the finger courses, the finger courses will be released, and the lifting fork may be moved away, leaving the bricks where placed.

1. A lifting fork comprising tw'o parallel members, a rst vertical pivot pin mounted on one of said members, an operating rod mounted for lateral movement on said member, an adjusting block, means including a threaded element for supporting the adjusting block on the operating rod adjacent said rst pivot pin, a resilient rod Wrapped loosely about the first pivot pin for at least a full turn, means to provide operative, en-

gagement between a rst end of said resilient rod and they adjustment block, a pair of vertically spaced clamping plates joined at a medialpoint by a second vertical pivot pin, the second pivot pin being hingedly secured to the second end of the resilient rod, and clamping means provided on the other of said members, so that movement of the operating rod in one direction will cause material positioned between said members to be gripped resiliently between vthe clamping plates and said clamping means, and movement of the operating rod in the other direction will retract the clamping plates away from said material.

2. A lifting fork comprising two parallel members, a first vertical pivot pin mounted on each of said members, an operating rod mounted for lateral movement on each of said members, a resilient rod wrapped loosely about each of said rst pivot pins for at least a full turn, means to provide an operative engagement between one end of each of the resilient rods and their respective operating rods, means to support a second pivot pin on the other end of each of the resilient rods in spaced parallel relationship to said first pivot pin, a clamping element for each of the resilient rods supported at a medial point by their respective pivot pins, common actuating means for said operating rods, so that movement of the operating rods in one direction will cause said clamping elements to resiliently grip material positioned between said members, and movement of the operating rods in the other direction will cause the clamping elements to be retracted. 3. A lifting fork comprising three parallel members, a pair of movable clamping means .on the central member and clamping means provided on each of the outer members, one of the movable clamping means on the central member cooperating with the clampmg means provided on one of the outer members, the other of the movable clamping means on the central member cooperating with the clamping means provided on the other of the outer members to resiliently grip material positioned between said members, each of said movable means comprising a rst pivot pin vertically positioned on the central member, a resilient rod wrapped loosely around the first pivot pin, a second pivot pin supported on a rst end of the resilient rod in spaced parallel relationship to the rst pivotpin, and a clamping plate supported at a medial point by said second pivot pin, operating means for the movableA tal members disposed in lcooperative relationshipto the mst-mentioned clamping means so as to act upon material placed between said horizontal members when moved in one direction, and to release said material when moved in the `other direction, linkage means operatively connecting said movable clamping means, said movable frame and said supporting means so that relative movement of the supporting means with respect to the movable frame in an upward direction will cause said linkage means to exert a force having a ilrst component tending to lift the movable s frame and a second component tending to cause the movable clamping means to act on said mai atively engage an outwardly extending end oi' one of the coil springs, a clamping element pivotally mounted on the other end or each of the coil `springs and adapted to engage material to be handled, and a common actuating means for said operating rods, said coil springs being disposed so that said clamping elements cooperate to act upon material positioned between said lparallel tine members.

7. A lifting fork comprising three parallel tine members, two coil springs mounted on the intermediate member of said three tine members, the

axis of each coil extending vertically and each spring having outwardly extending end portions for horizontal pivotal movement about the axes of said coils, an operating rod mounted for lateral movement along said intermediate tine member, means on said rod to operatively engage one o! the outwardly extending ends of each of the coil one of the outwardly extending ends of said spring, a first clamping element pivotally mounted on the other end of said coil spring and adapted to engage material to be handled, and a second clamping element provided on the other of said tine members cooperating with said first clamp#- ing element to act upon material positioned between said tine members.

6. A lifting fork comprising two parallel tine members, each of said tine members being provided with a coil spring, the axis of the coil extending vertically and having outwardly extending end portions, an operating rod mounted on each of said tine members laterally of said coils for movement lengthwise of eachof said tine members, means on each of said rods to opersprings on ,said intermediate tine member, a clamping plate pivotally mounted on the other end of the coil springs, clamping means provided on each of the other two tine members on said side thereof facing said intermediate tine member, said coil springs being disposed on opposite sides of said operating rod so that said clamping means cooperate to act upon material positioned between said parallel tine members.

VICTOR H. CARTWRIGHT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

